How Can Sustainable Infrastructure Help to Mitigate Climate Change Challenges?

More than half of the world's population now lives in cities, and cities produce a large share of global greenhouse gas emissions; urban infrastructure is therefore central to climate change mitigation. This paper explores how sustainable urban infrastructure, that is, public transportation, renewable energy systems, green buildings, water management and urban planning, can reduce emissions and also improve living conditions, and why some cities have built it better than others. Four cities enter the study: Copenhagen and Curitiba as relatively successful cases, and Los Angeles and Jakarta as cases with more complicated results. Cycling networks, bus transit joined to land-use planning, urban parks and their funding, and mass rapid transit are all included in the comparison. Four conditions emerge from these four cases. First, infrastructure works better if planners treat it together with land use and pedestrian access instead of constructing it as a separate project. Second, investment and government support are necessary, but a large budget does not guarantee a good result; the low-cost bus system of Curitiba shows this. Third, the benefits do not spread equally on their own; in Los Angeles the competitive park funding process repeated the inequality that it was set up to correct. Fourth, sustainable infrastructure needs continuous monitoring, maintenance and adjustment, and no city should treat it as finished once construction ends. Therefore, sustainable infrastructure should be judged by whether residents can reach it and use it, and not by its physical presence alone.